Sewing machine construction

ABSTRACT

A sewing machine having a mechanism for operatively disengaging a needle from a needlebar when the needle hits an impenetrable object. The needle is provided with a transverse slot which normally engages the end of a movable pin which pin holds the needle in fixed relation to the needlebar. An adjustable spring in turn tensions the pin to a preselected position whereby excessive forces on the needle occasioned by hitting an impenetrable object overcomes the force exerted by the spring on the pin thereby allowing operative disengagement of the needle from the needlebar.

United States Patent Felix .I. Berube 153 River Street, Sanford, Maine 04073 785,657

Dec. 20, 1968 June 1, 197 l Inventor Appl. No. Filed Patented SEWING MACHINE CONSTRUCTION 8 Claims, 2 Drawing Figs.

US. Cl 112/226 Int. Cl. D05b 55/02 Field of Search 112/226 References Cited UNITED STATES PATENTS 204,294 5/1878 Cook et a1. 112/226 12/1918 Garbus 112/226 FOREIGN PATENTS 621,565 6/1961 Canada Primary Examiner-Richard J. Scanlan, Jr. AttorneyWolf, Greenfield and Sacks SEWING MACHINE CONSTRUCTION SUBJECT MATTER OF INVENTION The present invention relates to an improved means for operatively disengaging a needle from a needlebar when the needle hits an impenetrable or like object.

"BACKGROUND OF INVENTION Sewing machines for industrial or home use may easily be damaged by malfunctions or misuse of the machine. For example, in stitching zippers, buckles, snaps, buttons and other metal or hand attachments to a fabric, it is quite possible to inadvertently bring the metal or hard portion of an article into the path of the needle. In such an event the needle will usually break or bend before the machine can be stopped. The broken or bent needle may damage the fabric being stitched or further damage the sewing machine. A broken or bent needle or even a needle which is slightly misaligned or deflected can readily strike the sewing machine plate or some other mechanism below the plate, necessitating delays and expensive repairs. In addition such a malfunction may jam the needle which in turn may cause the sewing machine motor which continues to operate during the jam to burn out. In addition the misuse or malfunctioning of the machine may cause injury to the operator. Such and injury may occur, for example, when the operators fingers are close to the needle at the moment the needle is bent or broken when it strikes a resistant material such as a zipper or button. Such problems are particularly acute in high speed industrial machines.

Attemptsto overcome these problems have been directed primarily to means for disengaging the needlebar from the drive mechanism; In many instances such solutions require especially designed and expensive needlebars which frequently must be carefully set by an experienced sewing machine mechanic. Such apparatus is consequently expensive to manufacture and maintain.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome these and other problems by providing a sewing machine construction which is, not likely to jam or malfunction when the pointed end of a needle hits resistant material. It is also an object of the present invention to provide an improved sewing machine construction in which needle breakage or damage for the reasons such as set forth above are minimized or substantially eliminated. A further object of the present invention is to provide? a sewing machine construction in which damage to the sewing machine and to its component parts and injury to operators are minimized. A still further object of the present invention is to provide a relatively simple modification of a needle and collar for attaching a needle to a needlebar which effectively automatically disengage a needle when it hits an impenetrable object. A further object of the present invention is to provide a simple means for interengaging a needle with a needlebar in a manner which permits automatic disengagement of the needle from the needlebar when the needlebar meets unusually resistant materials. A further object of this invention is to provide a means for operatively interengaging a needle with a needlebar which means permits disengagement of the needle from the needlebar at selectively controlled levels of force, with the selected level of force necessary being controlled over a wide but specifically defined range.

In the present invention there is provided a needlebar having an axially extending hole from one end within which a needle is adapted to fit. The needle is formed with a transverse slot near its upper end that is engaged by a pin which extends angularly through the wall of the needlebar with one end engaging the slot of the needle and the other being maintained against axial movement by a stop which in turn is secured under tension in a selected stop position by an adjustable spring.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of the present invention will be more clearly understood when considered in conjunction with the accompanying drawings in which:

FIG. 1 is a vertical fragmentary cross section of a needlebar assembly and needle embodying the present invention; and

FIG. 2 is a cross sectional view taken along the line 22 of FIG. ll.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings there is illustrated a conventional needlebar l which has an upperend 2 that may be suitably attached to the drive mechanism of a sewing machine as for example a home or industrial sewing machine. The lower end 3 of the needlebar has an elongated hole 4 formed in it with the hole 4 extending axially upwardly into the needlebar a distance sufficient to receive the entire needle which is connected to the needlebar. The needle 5 has a lower end which is conventional in nature. The upper end of this needle is formed with a transverse slot 6. This slot preferablyhas a semicylindrical wall extending normal to the axis of the needle, with a diameter somewhat less than half but preferably more than one fourth of the diameter of the needle. The needlebar l is also formed with a hole 7 that extends radially through it near the lower end 3. The hole 7 has a diameter which is preferably at least equal to the diameter of the slot or groove 6. The needlebar may be formed with a flattened portion 8 from which the hole 7 extends. A collar 9 is formed with a sleeve 10 having an opening through which the needlebar 1 extends. A sleeve with a threaded opening 11 extends normal to and from the opening defined by the sleeve 10. A support 14 comprises a pin support segment 15 and an integrally formed spring support 16. The pin support segment 15 comprises an externally threaded sleeve segment which is adapted to threadedly engage the opening in sleeve 11. The pin support is formed with an axially extending opening 17 having a diameter sufficient to receive and support a pin 18. The pin 18 is formed with a rounded end 19 having a diameter adapted to snugly engage the slot 6. The other end of the pin 18 extends into the spring support means 16. This spring support segment 16 is preferably formed with an enlarged end 22 that may have a knurled outer surface that is adapted to be engaged and rotated with ones fingers. This enlarged segment 22 is formed with a recess 23 defining a shoulder section 24 adjacent to the hole 17. Within the recess 23 is a plate 25 that bears on one surface against the adjacent end 20 of the pin 18 and limits its movement in an axial direction to the right (as shown in FIG. I). This plate retains the pin 18 so that its end 19 normally engages the slot 6. Since movement of plate 25 is limited by the shoulder 24 there is no tension normally exerted on the pin 18 when in the position as illustrated in FIG. I. On the other side of plate 25 there is positioned a heavy helical spring 26 that has one end bearing against the plate 25 and the other end engaging a setscrew 27. Setscrew 27 is threaded into the recess or hole 23 and may be conventionally adjusted by threading it into the hole to any desired degree thereby increasing or decreasing the tension or force of the spring 26 on plate 25.

In operating the needlebar assembly, the needle 5 is normally maintained in fixed interengagement with the needlebar l by interengagement of the slot 6 with the end 19 of the pin 18. When an unusually strong force is applied to the needle which will for example occur when the needle hits an impenetrable object, the axial forces on the needle cause it to move further into the hole 4 and in this connection a portion of this force is transmitted axially to the pin 18 so that it bears against the plate 25 forcing it to the right, as viewed in FIG. 1 against the tension of spring 26. If the force is sufficient the pin 18 will be forced from the slot 6 against the tension of the spring 26 thereby allowing the needle 5 to move further into the hole 4. The degree of force required to deflect the pin 18 may of course be adjusted by adjusting the setscrew 27. Such adjustments of the setscrew 27 will however not reduce the amount of force required to dislocate needle 5 below a fixed force determined by the curvature of the inner end 19 and the slot 6.

Attention is directed to elongated slot 30 which extends through the wall of the needle bar 1 into hole 4. This slot 30 is wide enough and long enough to permit insertion of a narrow key above the needle 5 when it has been forced upward into hole 4. The needle'5 may thus be properly realigned by moving the key down to the bottom of slot 30 which automatically properly locates the needle longitudinally with respect to the needle bar for interengagement with pin 18.

lclaim:

l. A needle bar assembly comprising a needle bar having an elongated hole extending axially from one end and a needle having the shank portion thereof inserted in said elongated hole and a second hole extending angularly to and intersecting the first hole through the side of said needle bar, said needle shank having a concave transverse slot formed therein, a collar engaging said needle bar and having an opening extending radially therethrough, a pin positioned in said opening of said collar with one end being convex and projecting through said second hole and engaging said concave transverse slot in said needle, means abutting the other end of said pin, and spring means tensioning said abutting means to a preselected tension in engagement with said pin, said elongated hole being of such a length so that when said pin is in engagement with said transverse slot of said needle shank, said elongated hole extends considerably beyond the end of said shank of said needle disposed within said elongated hole said concave transverse slot and said convex end of said pin being contoured so that when the point of said needle contacts an inpenetrable object during the downstroke of said needle bar, said transverse slot and convex end of said pin will become disengaged in opposition to the force of said spring means whereby said needle may be displaced upwardly into said elongated hole as the downstroke of said needle bar continues.

2. A needle bar assembly as set forth in claim I having a support means for said pin and said abutting means comprising a sleeve positioned in said collar opening and through which said pin extends, a cylindrical member having an opening coaxial and continuous with said sleeve, a shoulder within said coaxial opening, said abutting means comprising a plate normally in engagement with said shoulder and engaging said pin on one side and said spring means engaging the other side of said plate.

3. A needlebar assembly as set forth in claim 2 wherein said spring means comprises a helical spring within said coaxial opening and a setscrew adjustably securing said helical spring therein.

4. A needlebar assembly as set forth in claim 2 wherein said sleeve is formed with a threaded outer surface in threaded engagement with said collar.

5. A needlebar as set forth in claim 3 wherein said pin has a rounded end adapted to engage said slot of said needle.

6. A needlebar assembly as set forth in claim 1 wherein said needlebar is formed with a slot extending longitudinally thereof through the side thereof into said first hole.

7. A needlebar assembly as set forth in claim 6 wherein said slot terminates above said transverse slot.

8. A needle bar assembly comprising a needle bar having an elongated hole extending axially therein from one end thereof, said hole being receptive to the shank portion of a needle; detent means supported by said needle bar and having a portion thereof in communication with said elongated hole for engagement with a receptive transverse slot formed in the shank of said needle; means biasing said detent means toward said elongated hole; and a slot formed in said needlebar, said slot extending longitudinally of said needle bar and effecting communication between the exterior of said needle bar and said elongated hole, said slot extending along a substantial length between the end of said elongated hole and said detent means. 

1. A needle bar assembly comprising a needle bar having an elongated hole extending axially from one end and a needle having the shank portion thereof inserted in said elongated hole and a second hole extending angularly to and intersecting the first hole through the side of said needle bar, said needle shank having a concave transverse slot formed therein, a collar engaging said needle bar and having an opening extending radially therethrough, a pin positioned in said opening of said collar with one end being convex and projecting through said second hole and engaging said concave transverse slot in said needle, means abutting the other end of said pin, and spring means tensioning said abutting means to a preselected tension in engagement with said pin, said elongated hole being of such a length so that when said pin is in engagement with said transverse slot of said needle shank, said elongated hole extends considerably beyond the end of said shank of said needle disposed within said elongated hole said concave transverse slot and said convex end of said pin being contoured so that when the point of said needle contacts an inpenetrable object during the downstroke of said needle bar, said transverse slot and convex end of said pin will become disengaged in opposition to the force of said spring means whereby said needle may be displaced upwardly into said elongated hole as the downstroke of said needle bar continues.
 2. A needle bar assembly as set forth in claim 1 having a support means for said pin and said abutting means comprising a sleeve positioned in said collar opening and through which said pin extends, a cylindrical member having an opening coaxial and continuous with said sleeve, a shoulder within said coaxial opening, said abutting means comprising a plate normally in engagement with said shoulder and engaging said pin on one side and said spring means engaging the other side of said plate.
 3. A needlebar assembly as set forth in claim 2 wherein said spring means comprises a helical spring within said coaxial opening and a setscrew adjustably securing said helical spring therein.
 4. A needlebar assembly as set forth in claim 2 wherein said sleeve is formed with a threaded outer surface in threaded engagement with said collar.
 5. A needlebar as set forth in claim 3 wherein said pin has a rounded end adapted to engage said slot of said needle.
 6. A needlebar assembly as set forth in claim 1 wherein said needlebar is formed with a slot extending longitudinally thereof through the side thereof into said first hole.
 7. A needlebar assembly as set forth in claim 6 wherein said slot terminates above said transverse slot.
 8. A needle bar assembly comprising a needle bar having an elongated hole extending axially therein from one end thereof, said hole being receptive to the shank portion of a needle; detent means supported by said needle bar and having a portion thereof in communication with said elongated hole for engagement with a receptive transverse slot formed in the shank of said needle; means biasing said detent means toward said elongated hole; and a slot formed in said needle bar, said slot extending longitudinally of said needle bar and effecting communication between the exterior of said needle bar and said elongated hole, said slot extending along a substantial length between the end of said elongated hole and said detent means. 